TSL2568 Datasheet, PDF (5/36 Pages) TEXAS ADVANCED OPTOELECTRONIC SOLUTIONS – LIGHT-TO-DIGITAL CONVERTER

TSL2568, TSL2569
LIGHT-TO-DIGITAL CONVERTER
TAOS091D − DECEMBER 2008
NOTES: 2. Optical measurements are made using small-angle incident radiation from light-emitting diode optical sources. Visible 640 nm LEDs
and infrared 940 nm LEDs are used for final product testing for compatibility with high-volume production.
3. The 640 nm irradiance E_e is supplied by an AlInGaP light-emitting diode with the following characteristics: peak wavelength
λp = 640 nm and spectral halfwidth Δλ½ = 17 nm.
4. The 940 nm irradiance E_e is supplied by a GaAs light-emitting diode with the following characteristics: peak wavelength
λp = 940 nm and spectral halfwidth Δλ½ = 40 nm.
5. Integration time T_int, is dependent on internal oscillator frequency (f_osc) and on the integration field value in the timing register as
described in the Register Set section. For nominal f_osc = 735 kHz, nominal T_int = (number of clock cycles)/f_osc.
Field value 00: T_int = (11 × 918)/f_osc = 13.7 ms
Field value 01: T_int = (81 × 918)/f_osc = 101 ms
Field value 10: T_int = (322 × 918)/f_osc = 402 ms
Scaling between integration times vary proportionally as follows: 11/322 = 0.034 (field value 00), 81/322 = 0.252 (field value 01),
and 322/322 = 1 (field value 10).
6. Full scale ADC count value is limited by the fact that there is a maximum of one count per two oscillator frequency periods and also
by a 2-count offset.
Full scale ADC count value = ((number of clock cycles)/2 − 2)
Field value 00: Full scale ADC count value = ((11 × 918)/2 − 2) = 5047
Field value 01: Full scale ADC count value = ((81 × 918)/2 − 2) = 37177
Field value 10: Full scale ADC count value = 65535, which is limited by 16 bit register. This full scale ADC count value is reached
for 131074 clock cycles, which occurs for T_int = 178 ms for nominal f_osc = 735 kHz.
7. Low gain mode has 16y lower gain than high gain mode: (1/16 = 0.0625).
8. The sensor Lux is calculated using the empirical formula shown on p. 22 of this data sheet based on measured Ch0 and Ch1 ADC
count values for the light source specified. Actual Lux is obtained with a commercial luxmeter. The range of the (sensor Lux) / (actual
Lux) ratio is estimated based on the variation of the 640 nm and 940 nm optical parameters. Devices are not 100% tested with
fluorescent or incandescent light sources.
AC Electrical Characteristics, V_DD = 3 V, T_A = 255C (unless otherwise noted)
PARAMETER^†
TEST CONDITIONS
MIN
t_(CONV)
Conversion time
12
Clock frequency (I²C only)
0
f_(SCL)
Clock frequency (SMBus only)
10
t_(BUF)
Bus free time between start and stop condition
1.3
t_(HDSTA)
Hold time after (repeated) start condition. After
this period, the first clock is generated.
0.6
t_(SUSTA)
Repeated start condition setup time
0.6
t_(SUSTO)
Stop condition setup time
0.6
t_(HDDAT)
Data hold time
0
t_(SUDAT)
Data setup time
100
t_(LOW)
SCL clock low period
1.3
t_(HIGH)
SCL clock high period
0.6
t_(TIMEOUT) Detect clock/data low timeout (SMBus only)
25
t_F
Clock/data fall time
t_R
Clock/data rise time
C_i
Input pin capacitance
† _{Specified by design and characterization; not production tested.}
TYP
100
MAX
400
400
100
UNIT
ms
kHz
kHz
μs
μs
μs
μs
0.9 μs
ns
μs
μs
35 ms
300 ns
300 ns
10 pF
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Copyright E 2008, TAOS Inc.
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